Property-composition relationships for potentially bioactive glasses

Abstract

The compositional dependence of thermal expansion, A (in 10¯⁶ K¯¹), transformation temperature, Tg (in °C), dilatometric softening point. Mg (in °C), and viscosity, η (in dPa s), was determined for low-silica glasses in the S y s t e m Na₂O - K₂O - MgO - CaO - -Β₂O₃-Ρ₂O₅-SiO₂. The following phenomenological equations were established: A = 3.625 + 0.345p_Na₂O + 0.266p_K₂O + 0.098p_CaO + 0.064p_P₂O₅ , Tg = 635.9 - 5.26p_Na₂O + 3.18p_K₂O- 3.16p_MgO - 0.47p_Na₂O*p_K₂O - 0.12p_K₂O * p_CaO , Mg = 790.6 - 17.83p_Na₂O - 5.79p_K₂O + 0.28p²_Na₂O - 0.39p²_MgO where p_ is oxide content in wt%. The viscosity was modelled to f i t an Arrhenius-type equation, lgη = A + B/T. Giving η in dPa s, the compositional dependence of A and Β were found as A = - 55.707 + 0.597p_Na₂O + 0.591p_K₂O + 0.604p_MgO + 0.516p_CaO + 0.429p_P₂O₅ + 0.387p_SiO₂, Β = - 9 1 . 4 6 3p_Na₂O + 162.861p_CaO + 485.020p_Β₂O₃ + 249.200p_P₂O₅ + 285.212p_SiO₂·